How to type copyright symbol, trademark symbol etc in linux?

 As our qwerty keyboard can't accommodate all the available characters, symbols we end up with the keyboard(layout) that have the main and most widely used symbols, characters(with shift, alt key combinations).  But, in my opinion our keyboard should at least add symbols like Copyright  ©, Registered  ®, Trademark symbol ™.

Usually we do get/input these symbols from:

1. From a text editor program or from office suite(from insert symbols) like libreoffice, MS office etc.

2. From internet web pages by searching terms like "copyright symbol", "Trade mark symbol"

But, it is not possible to go every time into those application or to search with google to get/input these symbols.  So, Here is a easy way to input these symbols with your standard English keyboard layout (qwerty layout).  You have to enable some already available keyboard settings(Compose key) but not enabled by default .

So, with the help of compose key we can achieve this in our standard key board itself.

Compose key: A excerpt from wikipedia
"A compose key, available on some computer keyboards, is a special kind of modifier key designated to signal the software to interpret the following (usually two) keystrokes as a combination in order to produce a character not found directly on the keyboard. For example, striking Compose followed by ~ and then n can produce character ñ, whereas striking Compose followed by O and then C can produce the symbol ©, the copyright symbol). "

How to enable
1. In  BOSS linux(or any linux which have menu like Applications, System)
System -> preferences -> keyboard settings -> Layout settings -> options -> Compose key positions
In Ubuntu
Settings -> Keyboard -> Layout settings -> Options -> Compose key positions

2. Select your desired compose key.
   You can select any listed key(ctrl, win, capslock etc) as your compose key.  But, as we are using Linux, It is recommended to use the win(dows) key as compose key.

3.  Save the settings thats all you are done.

There are many symbols and the key combinations to produce it.  I here list few most often used symbols and its compose key combinations.  I assume win(dows) key  as the compose key.

Symbol Name	Symbol	composekey combination
Copyright	©	win+o then c
Trademark	™	win+t then m
Registered symbol	®	win+o then r
Quarter	¼	Win+1 then 4
Half	½	Win+1 then 2
3 quarters	¾	Win+3 then 4
Euro	€	win+e then =
Yen	¥	win+y then =
Pound	£	win+l then -
cent	¢	win+c then |
degree	°	win+o then o

Note:  This is for the debian based linux machines(like Ubuntu, BOSS Linux etc) which employs gnome desktop environment.  If your machine is not a debian based one or it uses other desktop environment systems(like kde, xfce etc), you have to fine where the keyboard setting is available and need to enable the settings as above.